A conventional electromagnetic brake or electromagnetic clutch includes an armature that is attracted by a magnetic force to an attraction target member. The armature and the attraction target member are made of a metal. For this reason, when the armature is attracted by a magnetic force to the attraction target member, a strike sound as a metallic sound is generated by the collision of the metal members. The strike sound may give an unpleasant feeling or instability, and is preferably as small as possible.